Evolutionary History of Rhacodactylus

[architeuthis]

It struck me yesterday how little of the natural history of these geckos I know. I started to do some cursory poking around on the internet, and found this, a paper from the australian zoological society on karotypes of rhacs:

http://www.publish.csiro.au/paper/ZO9900219

Does anyone know any of the formal biology? I'm not a biologist, but this stuff fascinates me. It would seem that cresteds are a recent island radiation from a mainland species. It also would seem that saras and ciliatus split off from the line together more recently than some of the others. Just speculation, but would make sense as they will hybridize with each other. I've been looking online for cladistic analysis, but what I do find of it is quite technical, and I'm not finding a lot. I wonder if leachies are an example of island giantism, where they began as crested sized animals and exploited a new island niche, thereby increasing their size over time.
Just thought it might be an interesting topic for discussion.

[Heather]

Good theories. I feel like I find an awful lot of "I don't know"s about Cresteds and to be honest part of me has given up on the research end of things.
 I think a lot of the hobbyists are more interested in the husbandry aspects...That being said I'm still working on my weight charts and egg growth charts and all the rest (all in the name of science, right?).  Make sure you post if you run across any good tid-bits.

[architeuthis]

It seems like there's this dearth of good science there. The practical aspects of keeping are great, and I like reading about that too, but surely we can't be the ONLY people interested in this.

[Leif]

Aaron M. Bauer puts out a lot of great reads. I have yet to read the one you came across so thank you!

[Heather]

Asked a knowledgable friend about this, and he suggested that all rhacs are a descendant of diplodactylus. Sortof looks like a crestie crossed with a leopard gecko.

[architeuthis]

That's very interesting. I wonder what traits are basal and what are newly evolved. I'm guessing crests are newly evolved and are some kind of sexual signifier, like a peacock's tail? Sarasinorims look almost like they're on the way to evolving the crests, esp. the white fringed individuals.

[architeuthis]

http://www.forums.repashy.com/general-gecko-talk/36148-phylogenetic-relationships-among-rhacodactylus.html

Relevant!

[dragonlets]

That's very interesting. I wonder what traits are basal and what are newly evolved. I'm guessing crests are newly evolved and are some kind of sexual signifier, like a peacock's tail? Sarasinorims look almost like they're on the way to evolving the crests, esp. the white fringed individuals.

I think it's unlikely that the crests are under sexual selection, since - as far as I know - there's no marked sexual dimorphism in crests; females can have just as big, or small, crests as males. (Unless wild-type individuals are sexually dimorphic? I don't know anything about the wild types, and it's hard to hypothesize about natural selection when your source material is all lineages that have been under artificial selection for generations.)

[architeuthis]

Good point. I was reading recently that the crests may serve as "pseudo-eyelids" and to help move foliage out of the way.